1. Technical Field
The present invention relates to a packaging material formed to have different sealing strengths region by region and heat-sealed to a second packaging material and to a packaging bag manufactured by using such packaging material.
2. Related Art
Conventionally, a variety of kinds of packaging bags have been used for packaging various substances. As one of such packaging bags, there has been provided a packaging bag preferred to contain different kinds of substances, such as liquids.
Such a packaging bag is formed as a single bag member, but has a plurality of partitions in which different kinds of substances are contained, respectively, and whenever necessary, the substances are made to be mixed with each other within the same bag. Practically, the packaging bag includes a sealed portion, whose sealing strength is weaker, that resides at a dividing portion between the partitions. When necessary, the bag is pressed to separate the sealed portion between two packaging materials, thereby the contained substances communicating with each other to be mixed.
Conventionally, to produce relatively weaker and stronger sealing portions, a particular resin film has been adopted and temperature and pressing pressure necessary for a heat-sealing process have involved adjustment operations.
However, the use of such special resin film results in a higher manufacturing cost. Moreover, adjusting the temperature and pressing pressure for the heat-sealing process requires difficult and troublesome adjustment work. What is worse, it is not always true that a desired sealing strength is obtained, even if such factors as temperature and pressing pressure are adjusted precisely. Thus, the sealing strength varies widely, thus resulting in unstable sealed quality.